Control apparatus for an air conditioning system

Abstract

A control apparatus for an air conditioning system has an outdoor unit with a compressor, a condenser and a plurality of motorized valves installed to a plurality of branch pipings. A plurality of indoor units having, a plurality of indoor thermoswitches, a microcomputer, and a drive circuit for driving the motorized valves according to the output from the microcomputer are also provided for the control apparatus. The microcomputer counts the number of indoor units required for operation by receiving the output from the indoor thermoswitch. The microcomputer also controls the opening of the motorized valves by predetermined opening steps, according to the result of the counting and with reference to an opening table. The opening table relates the number of indoor units required for operation with the opening of each of the motorized valves. The control apparatus thus permits an optimum distribution of refrigerant to the indoor units to be set quickly.

We claim: 
     
       1. A control apparatus for an air conditioning system comprising: an outdoor unit which has a compressor, a condenser to receive refrigerant transferred from said compressor, a liquid refrigerant pipe which is connected to said condenser at one end thereof and is divided into a plurality of branch pipes at the other end thereof, and at least one motorized valve being disposed in each of the branch pipes, the motorized valves controlling a quantity of refrigerant flowing in said branch pipes;   a plurality of indoor units which have respective evaporators, and which are connected to individual branch pipes through connection pipes;   operation request signal output means for outputting an operation request signal indicating which of the indoor units is required to operate;   specifying means for specifying which indoor units are required to be operated in response to the request signal from the operation request signal output means, said specifying means outputting a signal indicative of the specified indoor units;   counting means for counting the number of the indoor units required to operate in accordance with the request signal from said operation request signal output means;   valve-opening control means provided with a table representing degrees of valve opening for each of the motorized valves, the degrees being predetermined relative to a number of indoor units required to operate in a manner that valve openings decrease in steps as the number of indoor units required to operate increases, the valve openings also increasing in steps as the number of indoor units required to operate decreases, the valve opening means looking up the table to get the degree of valve opening corresponding to the number of the indoor units decided by the counting means and based on the signal indicative of the indoor units, said valve-opening control means outputting a signal representative of the degree of valve opening; and   drive circuit means for driving said motorized valves for the indoor units required to operate in response to the signal outputted from said specifying means and for controlling the motorized valves to open to the degree decided by the valve-opening control means in response to the signal outputted from the valve-opening control means.   
     
     
       2. The control apparatus for an air conditioning system as claimed in claim 1, further comprising capacity indicating means for selecting one value out of predetermined, discrete numerical values to set a capacity for each of said indoor units and for outputting a signal indicating the capacity, wherein the table represents degrees of valve opening for each of the motorized valves, the degrees being predetermined relative to the number of said indoor units required to operate and the capacity thereof in a manner that; when the capacity is constant, the valve opening decreases in steps as the number of indoor units required to operate increases, and when the valve opening increases in steps as the number of indoor units required to operate decreases; and   when a number of indoor units required to operate is constant, the opening of said motorized valves increases in steps as the capacity increases, and when the valve opening decreases in steps as the capacity increases;   said valve-opening control means looks up within the table of degree of valve opening corresponding to a combination of the number of indoor units required to operate and capacity decided based on the signal output from the counting means and the signal output from the capacity indicating means with respect to each of the indoor units required to operate, and outputs a signal indicative of the degree of valve opening.   
     
     
       3. The control apparatus for an air conditioning system as claimed in claim 1, further comprising pipe length indicating means for selecting one value out of predetermined, discrete numerical values to set a pipe length of each of the connection pipes and for outputting a signal indicating the pipe length, wherein the table represents degrees of valve opening for each of the motorized valves, which degrees are predetermined relative to the number of said indoor units required to operate and the pipe length of the connection pipes in a manner that; when the pipe length of the connection pipe is constant, the valve opening decreases in steps as the number of indoor units required to operate increases, and when the valve opening increases in steps as the number of indoor units required to operate decreases; and   when the number of indoor units required to operate is constant, the valve opening increases in steps as the length of the connection pipes increases in steps, and when the valve opening decreases in steps as the length of connection pipe decreases;   said valve-opening control means looks up within the table the degree of valve opening for a combination of the number of indoor units required to operate and pipe length of the connection pipes decided based on the signals from the counting means and length indicating means with respect to each of the indoor units required to operate, and outputs a signal indicative of the degree of valve opening.   
     
     
       4. The control apparatus for an air conditioning system as claimed in claim 1, further comprising capacity indicating means for selecting one value out of predetermined, discrete numerical values to set a capacity for each of the indoor units and for outputting a signal indicating the capacity, and further comprising pipe length indicating means for selecting one value out of predetermined, discrete numerical values to set a pipe length of each of the connection pipes and for outputting a signal indicating the pipe length, wherein the table represents degrees of valve opening for each of the motorized valves, which degrees are predetermined relative to the number of indoor units required to operate, the capacity of the indoor units and the pipe length of the connection pipes in a manner that; when the capacity of the indoor units required to operate is constant and the pipe length of the connection pipes are constant, the valve opening decreases in steps as the number of the indoor units increases, and when the valve opening increases in steps as the number of indoor units decreases;   when the number of the indoor units required to operate and the pipe length of the connection pipes are constant, the valve opening increases in steps as the capacity of the indoor units increases, and when the valve opening decreases in steps as the capacity of the indoor units increases; and   when the number of the indoor units required to operate is constant and the capacity of the indoor units are constant the valve opening increases in steps as the pipe length of the connection pipe increases and the valve opening decreases in steps as the pipe length of the connection pipe decreases;   said valve-opening control means looks up within the table the degree of valve opening for a combination of the number of the indoor units required to operate, capacity of the indoor units and pipe length of the connection pipes decided based on the signals from the counting means, capacity indicating means and pipe length indicating means with respect to each of the indoor units required to operate, and outputs signals indicative of the degree of valve opening.